Talks in Istanbul on Saturday among negotiators from Iran and six world powers including the United States represented "a positive first step" in addressing international concern over the Iranian nuclear program, the White House said.The parties in Turkey discussed Iran's nuclear program for the first time in more than a year and agreed to reconvene in Baghdad on May 23.The talks were never expected to yield any major breakthrough but diplomats believed a serious commitment from Iran would be enough to schedule another round of talks for next month and start discussing issues at the heart of the dispute.Saeed Jalili, the chief Iranian negotiator, told a news conference that “progress” had been made.“We witnessed progress,” Jalili said. “There were differences of opinion... but the points we agreed on were important.”“The next talks should be based on confidence-building measures, which would build the confidence of Iranians,” Jalili said, adding an Iranian request for lifting of sanctions should be one of the issues included.Iran has been hit by new waves of Western economic sanctions this year.Western participants had said previously that agreeing to meet for a second round of talks would constitute a successful day. It may remove some heat from a crisis in which warnings from Israel of a possible strike against Iranian facilities have stoked fears of a major war in an already unsettled Middle East.Israel made no comment Saturday on the talks in Istanbul, with one official explaining that any comment Israel would make at this time would not be “prudent.”“We are waiting to see how the talks play out,” the official said.Last week, Prime Minister Binyamin Netanyahu said the talks should lead to the removal from Iran of all enriched uranium, a halt to all further enrichment, and the closure of the underground nuclear facility at Qom.Defense Minister Ehud Barak set the bar a bit lower, saying that while Iran should have to give up its entire stockpile of uranium enriched to 20 percent, believed to be about 120 kilograms, and transfer the majority of its 5 tons of 3.5 enriched uranium out of the country, it would be able to keep a minimum amount for energy purposes.Barak also said Iran must open all of its nuclear facilities to the IAEA, disclose its entire history of activity relating to its nuclear weapons program, and suspend all enrichment activity. If Iran complied with these conditions, he said it would be possible to agree to an arrangement whereby a third country would transfer fuel rods to Iran for the purpose of activating the Tehran Research Reactor.Iran turned down a request by the US for a rare bilateral meeting on the sidelines of the nuclear talks in Istanbul on Saturday, the official Iranian news agency IRNA reported.There was no comment from US diplomats, whose country has not had direct ties with Tehran for more than three decades.IRNA’s report followed contradictory accounts from two other Iranian news agencies on prospects for a meeting between Jalili and the head of the US delegation, Under Secretary of State for Political Affairs Wendy Sherman.The US and Iran broke off diplomatic ties after the 1979 Islamic revolution which toppled the US-backed shah and both sides view each other with deep mistrust.“The Iranian delegation rejected the request of Wendy Sherman, the representative of the American delegation, for a bilateral meeting,” IRNA said.The semi-official Fars news agency had earlier quoted an “informed source” as denying a report by a third agency, ISNA, that Jalili accepted a request for a meeting with a US envoy.Non-Iranian diplomats attending the talks in Istanbul had questioned the ISNA report but still said Saturday’s meeting between Iran and the six powers – the United States, Russia, France, China, Germany and Britain – had gone well.IRNA said Iranian diplomats in Istanbul did hold bilateral meetings on Saturday with Russian delegates and with Ashton, the main representative of the negotiating group of international powers, as well with the Turkish hosts, who are not party to the negotiations.The talks between Iran and six world powers resumed after a 15-month gap, as delegates sought to find ways of resolving a dispute over Tehran’s nuclear program and easing fears of a new Middle East war.The West accuses Iran of trying to develop a nuclear-weapons capability. Iran says its program is peaceful. Tehran agreed to resume talks with the six – the five permanent members of the UN Security Council plus Germany – after more than a year of escalating rhetoric and tensions.One diplomat described the atmosphere as “completely different” from that of previous meetings, as Western delegates watched out for signs that Iran was ready to engage seriously after more than a year of threats and accusations.The talks are unlikely to yield any major breakthrough, but diplomats believe a serious commitment from Iran could be enough to schedule another round of talks for next month and start discussing issues at the heart of the dispute.“The atmosphere is constructive, the conversation is businesslike. As of the moment, things are going well,” Deputy Foreign Minister Sergei Ryabkov, who led the Russian delegation, was quoted as saying by Interfax news agency.Tehran agreed to resume talks with the five permanent members of the UN Security Council, plus Germany, after more than a year marked by escalating rhetoric and tensions.The US and Israel have not ruled out military action to destroy Iran’s nuclear sites.In the run-up to the Turkey meeting, Western diplomats said they hoped for enough progress to be able to schedule a new round of negotiations, possibly in Baghdad, next month.During the morning round of talks Iranian chief nuclear negotiator Jalili did not state the kind of preconditions that he did in the last meeting in early 2011, a diplomat said.“He seems to have come with an objective to get into a process which is a serious process,” the envoy said. “I would say it has been a useful morning’s work.”Iran says it will propose “new initiatives” in Istanbul, though it is unclear whether it is now prepared to discuss curbs to its enrichment program. But the atmosphere was positive.“They met in a constructive atmosphere,” said Michael Mann, a spokesman for Ashton, after the morning session of talks. “We had a positive feeling that they did want to engage.”Ashton, who is the main representative of the US, France, Russia, China, Germany and Britain at the talks, added: “What we are here to do is to find ways in which we can build confidence between us and ways in which we can demonstrate that Iran is moving away from a nuclear weapons program.”In a rare opinion piece in an American newspaper, the Iranian foreign minister took to the pages of The Washington Post Thursday to urge that the parties enter negotiations on a basis of mutual respect and equality.Ali Akbar Salehi wrote that it was important that “all sides will be committed to comprehensive, long-term dialogue aimed at resolving all parties’ outstanding concerns” and that “all sides make genuine efforts to reestablish confidence and trust.” He referred to Iran’s stated opposition to weapons of mass destruction and its continued willingness to enter a dialogue with world powers despite international sanctions.Yet he warned, “If the intention of dialogue is merely to prevent cold conflict from turning hot, rather than to resolve differences, suspicion will linger. Trust will not be established.”The United States cut diplomatic ties with Iran in 1980 after Iranian students held 52 American diplomats hostage for 444 days, and the two sides have held very rare one-to-one meetings since then.Iran, one of the world’s largest oil producers, says its nuclear program has solely peaceful objectives – to generate electricity and produce medical isotopes for cancer patients.But its refusal to halt nuclear work – which can have both civilian and military uses – has been punished with intensifying US and EU sanctions against its lifeblood oil exports.“Given that oil revenue accounts for over half of government income, the budget will be under significant strain this year as oil exports fall as a result of sanctions and oil production is cut back by Iran as its pool of buyers begins to shrink,” said Dubai-based independent analyst Mohammed Shakeel.Western officials have made clear their immediate priority is to persuade Tehran to cease the higher-grade uranium enrichment it began in 2010. It has since expanded that work, shortening the time it would need for any weapons “break-out.”Iran has signaled some flexibility over limiting its uranium enrichment to a fissile purity of 20% – compared with the 5% level required for nuclear power plants – but also suggests it is not ready to do so yet.Ben Rhodes, deputy national security adviser, said the United States sees room to negotiate over how Iran can meet international obligations under its nuclear program, which Tehran says is for energy and medical purposes but global powers fear is meant to create a weapon. Catherine Ashton, the European Union’s foreign policy chief who has headed negotiations for the six international powers including the United States and Russia, told a news conference after a day of talks in Istanbul that they arranged to meet the Iranian delegation again in Baghdad on May 23.“We want now to move to a sustained process of dialogue,” Ashton told a news conference, saying negotiators would take a “step-by-step” approach. “We will meet on May 23 in Baghdad.”“The discussions on the Iranian nuclear issue have been constructive and useful,” she said. “We want now to move to a sustained process of serious dialogue, where we can take urgent, practical steps to build confidence.”After a day in which diplomats had spoken of a more engaged tone from Iranian officials compared to the 15 months of angry rhetoric on either side that has filled the hiatus since the last meetings, Ashton called the talks useful and constructive.She said the negotiating powers wanted Iran to meet its international obligations – it is a signatory to the treaty which prevents the spread of nuclear weapons – and should reciprocate in negotiations.